Here's How To Do It:

Paint the Surface

Paint the surface with two coats of sky-blue latex paint. Let dry.

Create the Clouds

Dip a sea sponge into a bowl of water and squeeze out the excess. Dip the sponge into blue-gray latex paint and dab off any excess. Begin your clouds by randomly dabbing the paint across the sky-blue surface. Clouds begin to appear as blue-gray paint is dabbed across the blue-sky background.

Soften the Edges

While the paint is wet, gently dab a piece of cheesecloth over the entire surface. This softens the edges.

Repeat the procedure with a light-blue latex paint, dabbing over areas of gray. Don't let the paint dry between shades. Don't cover any painted areas completely -- let some of the sky-blue and blue-gray colors show through. With a piece of dry cheesecloth, smudge the light-blue painted areas while wet.

The Cloud Effect

Use white-white latex paint to highlight the overall cloud effect. Dab on sparingly, and smudge with a dry piece of cheesecloth.

A stormy sky can be created by using more of the blue-gray color or a windy sky by painting elongated dabs of color going in one direction.